This invention relates to a computer system including one or more storage systems, in particular, data copy in a virtualized environment in which a storage area is virtualized.
A storage system allocates a storage area having a predetermined capacity to a computer using the storage system. In order to effectively use a storage capacity of the storage system, it is desirable to allocate a storage area having a capacity required by the computer. With the increase in the amount of data handled by the computer, however, the capacity of the allocated storage area is sometimes found insufficient. On the other hand, if a storage area having a sufficiently large capacity is allocated in advance, the storage system can be prevented from suffering from a shortage of capacity. However, when the computer does not handle a large amount of data in practice, a part of the allocated storage area is not used to lower the usage efficiency of the storage capacity.
JP 2005-11316 A discloses a computer system including a virtualization system connected to a computer and a plurality of storage systems connected to the virtualization system. The virtualization system allocates a virtual volume of a predetermined size to the computer. Upon reception of an access request to the virtual volume from the computer, the virtualization system allocates an actual storage area (real area) of the storage system to the virtual volume according to the access request. When the size of the virtual volume is set sufficiently large, the virtual volume allows for the increase in the amount of data processed by the computer. Moreover, since a necessary real area is allocated when the virtual volume actually receives an access request from the computer, the storage capacity of the storage system can be efficiently used.
On the other hand, as techniques of protecting data stored in a storage system from system failures, disasters, or the like to continue operations, a local copy technique and a remote copy technique are known. The local copy is a technique of copying data in a storage area in a storage system to another storage area in the same storage system. The remote copy is a technique of copying data in a storage area in a storage system to a storage area in another storage system. The remote copy technique is described in JP 2003-122509 A, for example.